Background: Diagnosis and identification of patients with acalculous biliary pain, who would benefit from surgery, remains a significant clinical problem. The cholecystokinin (CCK) provocation test helps diagnosis, but lack of consistency limits its usefulness. Aim: To characterize the response of gallbladder muscle strips, from patients with acalculous biliary pain, to hormonal and muscarinic stimulation and to compare these with strips from gallstone patients and normal controls. Patients: Eleven patients with acalculous biliary pain were studied, 5 had a positive CCK test. Eight gallbladders from gallstone patients and 6 from partial hepatectomies were used for comparison. Methods: Muscle strips from the body and neck of the gallbladder were suspended in organ baths and dose-response curves were constructed for CCK-8 and carbachol. Results: In the acalculous group the strips from the body were less sensitive to carbachol than those of the neck. Conclusion: Since we found no differences in the CCK responses for the groups, it casts doubt over the effectiveness of the CCK test to diagnose acalculous biliary pain. Since carbachol sensitivity was different, it might be that a similar test using muscarinic stimulation would help in the diagnosis of this difficult group of patients. Copyright (C) 2000 S. Karger AG, Basel.